IT工程師數位筆記本

package org.hjb.component;

import java.lang.ref.SoftReference;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

/**
 * 本地緩存
 * 
 * 何錦彬 2017.02.24
 */
public class LocalMemory {

    // 數據
    static class CacheData {

        // 過期時間
        private Long invalidTime;

        private Object data;

        public Long getInvalidTime() {
            return invalidTime;
        }

        public void setInvalidTime(Long invalidTime) {
            this.invalidTime = invalidTime;
        }

        public Object getData() {
            return data;
        }

        public void setData(Object data) {
            this.data = data;
        }
    }

    private static Logger logger = LogManager.getLogger(LocalMemory.class);

    // 存儲本地緩存數據.用軟引用避免OutOfMemoryError
    static Map<String, SoftReference<CacheData>> localData = new ConcurrentHashMap<String, SoftReference<CacheData>>();

    public static final int MAX_SIZE = 10000;

    public static final int WARN_VALUE = 8000;

    /**
     * @param key
     *            緩存KEY
     * @param value
     *            緩存數據
     * @param timeOut
     *            超時時間，單位秒
     */
    public static void put(String key, Object value, Long timeOut) {

        if (localData.size() >= WARN_VALUE) {
            logger.warn("注意:本地緩存已經達到臨界值,size:" + localData.size());
        }
        if (localData.size() > MAX_SIZE) {
            logger.error("超出最大值:" + localData.size());
            return;
        }
        CacheData cacheData = new CacheData();

        long now = System.currentTimeMillis();
        long invalidTime = now + (timeOut * 1000);
        cacheData.setData(value);
        cacheData.setInvalidTime(invalidTime);
        SoftReference<CacheData> refCacheData = new SoftReference<CacheData>(cacheData);
        localData.put(key, refCacheData);

    }

    public static final Object get(String key) {
        SoftReference<CacheData> referenceData = localData.get(key);
        if (referenceData == null) {
            logger.debug("未找到數據，key => {}", key);
        }
        CacheData cacheData = localData.get(key).get();
        if (cacheData == null) {
            logger.debug("未找到數據，key => {}", key);
        }
        Long invalidTime = cacheData.getInvalidTime();
        if (invalidTime == null) {
            return null;
        }
        long now = System.currentTimeMillis();
        if (now > invalidTime) {
            // 清除緩存
            localData.remove(key);
            return null;
        }
        return cacheData.getData();
    }

    public static void put(String key, Object value, long time, TimeUnit unit) {
        put(key, value, unit.toSeconds(time));
    }

    public static void main(String[] args) throws InterruptedException {
        String key = "test";
        Object value = "hello world";
        LocalMemory.put("test", value, 1l);
        System.out.println(LocalMemory.get(key));
        Thread.sleep(2000);
        System.out.println(LocalMemory.get(key));
    }

}